Temperature responsive methacrylamide polymers with antibacterial activity

<正>A new methacrylamide monomer,hexylamine methacrylamide(MAHA),was synthesized and used in polymerizations.The homopolymer of MAHA and its copolymers were synthesized by free radical polymerization techniques with N-isopropyl acrylamide(NIPAAm) in two different compositions.The quaternization of the homopolymer and copolymers were carried out using 1-bromopropane.The copolymers with NIPAAm and a low MAHA content showed temperature-responsive behavior in an aqueous environment.The lower critical solution temperatures(LCSTs) of these polymers varied between 32℃and 44℃.The LCSTs of quaternized copolymers were higher than those of neutral copolymers because they were more hydrophilic.The obtained homopolymers and copolymers were tested for antibacterial activities against S.aureus and E.coli.The quaternized water-soluble copolymers showed antibacterial activities against S.aureus.The quaternization resulted in the synthesis of both antibacterial and temperature-responsive copolymers.     

Stepwise ordering of imidazolium-based cationic surfactants during cooling-induced crystallization

Surfactants bearing imidazolium cations represent a new class of building blocks in molecular self-assembly. These imidazolium-based cationic surfactants can exhibit various morphologies during phase transformations. In this work, we studied the self-assembly and phase behavior of 1-hexadecyl-3-methylimidazolium chloride (C(16)mimCl) aqueous dispersions (0.5-10 wt %) by using isothermal titration calorimetry, differential scanning calorimetry, synchrotron small- and wide-angle X-ray scattering, freeze-fracture electron microscopy, optical microscopy, electrical conductance, and Fourier transform infrared spectroscopy. It was found that C(16)mimCl in aqueous solutions can form two different crystalline phases. At higher C(16)mimCl concentrations (>6 wt %), the initial spherical micelles convert directly to the stable crystalline phase upon cooling. At lower concentrations (0.5 or 1 wt %), the micelles first convert to a metastable crystalline phase upon cooling and then transform to the stable crystalline phase upon further incubation at low temperature. The electrical conductance measurement reveals that the two crystalline phases have similar surface charge densities and surface curvatures. Besides, the microscopic and spectroscopic investigations of the two crystalline phases suggest that the metastable crystalline phase has preassembled morphology and a preordered submolecular packing state that contribute to the final stable crystalline structure. The formation of a preordered structure prior to the final crystalline state deepens our understanding of the crystallization mechanisms of common surfactants and amphiphilic ionic liquids and should thus be widely recognized and explored.     

血浆中极长链脂肪酸的毛细管气相色谱分析

建立了血浆中极长链脂肪酸毛细管气相色谱法，并用于测定了１０例正常人和４例临床拟诊为肾上腺白质营养不良（ＡＬＤ）病人血浆中极长链脂肪酸，其中一例肯定了ＡＬＤ的临床诊断。     

Intramolecular photoinduced electron-transfer in azobenzene-perylene diimide

This paper studies the intramolecular photoinduced electron-transfer (PET) of covalent bonded azobenzene-perylene diimide (AZO-PDI) in solvents by using steady-state and time-resolved fluorescence spectroscopy together with ultrafast transient absorption spectroscopic techniques.Fast fluorescence quenching is observed when AZO-PDI is excited at characteristic wavelengths of AZO and perylene moieties.Reductive electron-transfer with transfer rate faster than 10 11 s-1 is found.This PET process is also consolidated by femtosecond transient absorption spectra.     

Experimental and calculated momentum densities for the complete valence orbitals of the antimicrobial agent diacetyl

The first electronic structural study of the complete valence shell binding energy spectra of the antimicrobial agent diacetyl, encompassing both the outer and inner valence regions, is reported. The binding energy spectra as well as the individual orbital momentum profiles have been measured by using a high resolution （e, 2e） electron momentum spectrometer （EMS） at an impact energy of 1200eV plus the binding energy, and using symmetric noncoplanar kinematics. The experimental orbital electron momentum profiles are compared with self-consistent field （SCF） theoretical profiles calculated using the Hartree-Fock approximation and Density Functional theory predictions in the target Kohn-Sham approximation which includes some treatment of correlation via the exchange and correlation potentials with a range of basis sets. The pole strengths of the main ionization peaks from the inner valence orbitals are estimated.     

Low-energy electronic properties of a Weyl semimetal quantum dot

We investigate the low-energy electronic structure of a Weyl semimetal quantum dot(QD) with a simple model Hamiltonian with only two Weyl points. Distinguished from the semiconductor and topological insulator QDs, there exist both surface and bulk states near the Fermi level in Weyl semimetal QDs. The surface state, distributed near the side surface of the QD, contributes a circular persistent current, an orbital magnetic moment, and a chiral spin polarization with spin-current locking. There are always surface states even for a strong magnetic field, even though a given surface state gradually evolves into a Landau level with increasing magnetic field. It indicates that these unique properties can be tuned via the QD size. In addition, we show the correspondence to the electronic structures of a three-dimensional Weyl semimetal, such as Weyl point and Fermi arc. Because a QD has the largest surface-to-volume ratio, it provides a new platform to verify Weyl semimetal by separating and detecting the signals of surface states. Besides, the study of Weyl QDs is also necessary for potential applications in nanoelectronics.     

镱铒共掺Al2O3薄膜上转换机理及其温度特性

采用中频磁控溅射法制备了镱铒共掺Al2O3薄膜,铒镱掺杂浓度分别为0.3%,3.6%(摩尔分数,全文同).讨论了三价铒离子529 nm和549 nm光致发光的上转换机理.在291.8-573.3 K温度区间测量了两绿上转换光谱荧光强度比的温度特性,拟合表达式为R=5.37exp(-738/T).366 K温度时灵敏度最大,为0.0039 K-1.结果表明镱铒共掺Al2O3薄膜适合作为小型、高温和高灵敏的光学温度传感材料.     

Investigation of third-order nonlinear optical properties of two azo-nickel chelate compounds

This paper investigates the third-order nonlinear optical properties of two azo-nickel chelate compounds by the optical Kerr gate method at 830 nm wavelength with pulse duration of 120 fs. Both of the two compounds exhibited large third-order optical nonlinearity. The second-order hyperpolarizability,γ, of Compound 1 is of 1.0 × 10^-31 esu. Due to the charge transfer, the γ of Compound 2 with electron donor and acceptor group is 4.9 × 10^-31 esu, which is a four-time enhancement in comparison with Compound i. The absorption spectra show that the electron push-pull effect, which induces intramolecular charge transfer, leads to the increased optical nonlinearity.     

浓香型烤烟矿质元素含量的测定及分析

测定了河南省主产烟区烤烟K、Cl、Ca、Mg、S、P的含量,结果表明K的含量偏低,其他矿质元素含量正常.元素间的相关性分析结果表明多种矿质元素间存在极显著或显著的相关;对6种矿质元素含量进行因子分析得到2个因子,2个因子的累积贡献率为80.710％.